Man learns more from failures, therefore instead of lamenting, he should celebrate when he meets a failure. He should think that he has got an opportunity to understand his shortcomings and that he can act again after he corrects them.
The success does not provide him with the same opportunity,because it often stagnates him, makes him arrogant or makes him play safe.
Remember those who give up and accept failure, have a lustreless existence.
It is very important to act. The failure can teach many things. The man may realise that probably he had chosen a wrong goal and he could change it. If it is about love, he could even get a better partner, in the field of career it could be a different field also.
But If he wants to pursue the same goals he could learn from his failure. He could improve his plan, strategy, knowledge, skills, actions and implementation. He could even add on to his resources and strike once more with greater strength.
After successes, over a period the complacency sets in and even the empires fall , civilisations die on the other side even some ordinary men reach to the top positions, new empires rise and the churning goes on.